Cultural CornerРA letter from a Senior High StudentРWhat do you know about the high school system in the US?РTheir classes are lively and interesting.РTheir after-school activities are colorful.РThis is HarvardРThis is TsinghuaРThis is Cambridge University.РThis is University of Hongkong.РNinth to twelfth grades.РA high diploma.РRead the letter and answer the questions.Р① How long does secondary school cover in the US?Р② Which grades are high school? Р③ What do they need if they want to go to ? college?РSeven years.РParagraph 1: